Despatch system.



cf P. HIDDEN.

DESPATCH SYSTEM. l APPLICATION FILED FEB. 21. 1913.

11,142,429. Patented June 8,1915.

THE NDRRIS PETERS C0.. PHOW-LITHO.. WASHINGmN. D. C. l

Civ

z e l i I :i I

CHARLES P. HIDDEN, OF WINCHESTER, MASSACHUSETTS, ASSIGNOR TO' THEvLAMSON COMPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION OF-NEW JERSEY.

DESPATCH SYSTEM.

Specification of Letters Patent. i

Application filed February 21, 1913. Serial No. 749,841.

in this connection T desire to direct attentionV to the U. S. Letters Patent toJ. F. Slrirrow, No. 1,045,205, dated November 25, 1912. Herein, time element means are provided for insuring the continuance of a fiow of air through a transmission tube for a determined interval of time; such interval being' substantially I'iXed and invariable. T have found it, however, desirable, under certain conditions, that this time interval should be Y ade variable to a moderate degree in order V to accommodate variations in pressure in.

the carrier transmitting pressure-fluid,` e'. g. compressed air. l have also found' it desirable to provide in vconnection with a mo tor driven blower or pump, or other air'. displacing device, a reservoir within which the air may be stored and from which it be withdrawn for carrier transmission :pur-

poses, as desired. This insures an immediate delivery of pressure-fluid in adequate quantity without havingY to wait for the motor and blower to speed up tothepomt Vwhere the latter can deliver a volume of air under sufficient pressure to promptly start the carrier upon its gourney after it has been inserted in the receiving terminal. 'lvVhere such a reservoir is not provided andfwhere the blower is startedsubstantially upon the admission of the carrier tosaid receiving' terminal, it necessarily follows that the pressure must be more or-less increasingly but gradually built up until su'liicient pressure is attained te start the-carrienand while said pressure is thus being developed a certain seepage of air is apt to occur around the carrier so that while this interval is comparati vely short, there is nevertheless a certain waste of power. On the other hand where a reservoir is used without any such means as are hereinafter described formaintainingl pressure therein within determined limits, as the pressure-fluid is withdrawn from said reservoir, obviouslythe operating pressure of the system will gradually decrease. This results in a variable period of transmission of the carrier through a given transmission tube and 4hence if time element means -for controlling the 'iiow of air from suchreservoir be of such type as to render the system operative for a pre-determined and fixed intervaly of time, again a certain small waste ofy power will almost inevitably result.` l

My system, while it employs a .motor for generating mechanical power, does away with the frequent stopping and starting of this motorincident to the Shirrow motoroperated system .and hence effects a further saving of power. Since every time that the Vmotor and blower are started inertia has to be overcome. There isfa further loss of power in the case of asystem operated for a substantially pre-determined: interval of time, where suchsystern` comprises looped together or connected. transmission tubes, where the air for conveyingicarriers-in one direction is forced to first travelv through a tube .not directly used for out-going carriers l from a givenstation and thereafter from said tubet0 the tube `which conveys said carriers `from said station. This lossis due to the factL that the carrier propelling air current vneed flow but fora' shorter interval for carriers travelingfin one directionthan for those travelingy in an opposite direction, so that with the time interval fixed the same for both, and that of suiiicient duration for transmission purposes whereV the air flows around the loop, the said Yperiod is longer than is really needed about'onehalf the time. Another aim of this present invention is therefore to eliminate even this waste.`

Tt' is primarily,therefore, the object of the Y present inventioato provide such a system of fluid pressuregenerating and controlling apparatus as will effect an even greater economy of power than is possiblev with such constructions as are exemplified by Skirrow.

T iese and other objects of lmy invention Y will be hereinafter referred to and the novel elements vand combinations of` elements whereby said objects maybe attained will now be more fully described and thereafter particularly pointed out in theclaims ap pended hereto.

ln the accompanying drawing which forms a aart hereof I have somewhat dial y grammatically exemplified a preferred pneumatic despatch system of the kind 1n question.

1 am aware however that many changes and modifications may be made herein without departing from the spirit of my invention and hence desire to be limited only by the scope of said claims, broadly considered in the light of the disclosure'. Y

Referring to the drawing, two stations A. and B are therein shown as connected by transmission tubes 1 and 2. rlube 1 is provided with a receiving terminal 3 and a delivering terminal 4, while tube 2 is correspondingly provided with the receiving terminal 5 and delivering terminal G. Terminals 3 and 5, and 4 and G, respectively, may be of substantially identical construction. Terminals 4 and 5 are connected by a loop 7, or inY any other desired manner, so that air may flow from tube 1 into tube 2 via said terminals.

ln the apparatus given by way of eXem plilication, compressed air is used to propel the carriers, this air being stored in a tank or reservoir 8 and passing thence to tube 1, when needed, through a pipe 9, a timing device, broadly7 designated 10 and hereafter more fully described, and a pipe 11, which delivers directly into the receiving terminal The particular construction of the delivH ering terminal 6 constitutes no part of the present invention but for convenience may be briefly described. Pivoted within this terminal at12 is a bent lever 13 which has a slotted connection 14 with a valve 15; the latter being pivoted at 16 to the lower portion of the terminal and being normally held closed by spring 17.

When a carrier strikes the lever 13 upon emerging into terminal G it swings said lever to the left and thereby opens valve 15, permitting said carrier to escape. :immediately thereafter spring 17 causes the valve 15 and lever 13 to resume their normal positions and the air subsequently entering terminal 6 from the transmission tube 2, as also the air in advance vof said carrier, escapes y through the exhaust pipe 18.

Vand from thence, through connections hereinafter more particularly referred to, to a solenoid 24. The current thereafter passes through a second solenoid 25, variable resistance 26, wire 27 to the motor 21 and from thence through a wire 28 to a switch arm 29.

The reservoir S is provided with a cylinder 30 which is in free communication with said reservoir and within this cylinder is a piston 31. which is normally pressed inwardly toward said receptacle by a spring 32, disposed within said cylinder. This spring, it may be here noted, may be given any desired initial tension by screwing in or out, as desired, the nut or spring abutment 33. T he stem or rod 34 of the piston 31 carries upon its outer extremit;7 a contact plate 35, which plate is adapted for engagement with the free end of the above mentioned switch arm 29, the latter being pivotedly mounted at 35.

lVhen the pressure in the reservoir attains a determined amount it drives the piston 31 outwardly against the action of its spring and conversely when this pressure .is below said amount, piston 31 together with contact 35 will be moved inwardly by said spring until contact 35 has not only7 engaged the extremity of switch arm 29 and swung the latter to the left but has also engaged a contact 37, thereby completing circuit through the motor; current at such time passing from switch arm 29 through contact plate 35, contact 37 and wire 33 to a wire 39. Wv ire 39 leads to a contact 40 which is nor-- mally in engagement with a movable contact bar or plate 41, which latter is also normally in enga gement with a contact 42. The current therefore passes through these con* tacts to a wire 43 and from thence back to the double pole switch 44 and out through lead 45.

rlllhe energization of the motor circuit in thc'manner described effects the actuation of solenoid 24 above referred to, and the lifting of the core ofthis latter, short circuits the switch arm 29 and contacts 35 and 37; the motor circuit at such time being completed through contacts 46, 47 and 48 and from thence through wire 49 to wire 39 and out as before. rlhis combination of elements,operating in the manner described, results in the continued driving of the motor after it has once been started, regardless of the development of sufficient pressure in the reservoir 8 to force piston 31 outwardly and thereby break the partial circuit through the switch arm 29. rlhis switch arm is mechanically connected to a second switch arm 50 but is electrically insulated therefrom; movement of one of these arms in one direction or the other effecting a corresponding movement of the other arm. Switch arm 50 is adapted to be thrown into circuit with a battery 51, or other suitable source or current, and when the pressure in Ithe reservoir has attained its upper limit the piston 31 and contact 35. will at such time have been moved to the right, againstthe action of spring 32, until contact plate 35 engages a contact 52. At such time, also, it will further normally make contact with the free extremity of the arm 50; because in its previous movement to the left contact 35 will have swung the arm 29 to the left and thereby arm 50 correspondingly. To insure a proper disposition of the arms 29 and 50 in the positions into which fthey may be moved by theplate 35, one of these arms, e. g. 50, may be provided with a quadrant 54: the periphery of which may be suitably indented at two points for the reception of a spring pressed detent 55. Preferably, also, contacts 37 and 52 are resiliently mounted so as to insure proper contact. When the plate 36 so engages the arm 50 and contacts 52, current flows from the battery via wire 56 through a solenoid 57, wire 58 and a second solenoid 59, to thevv varm 50 and from thence through contactI plate 35 and contact 52 back to the battery..

This momentary closure 'ofthe battery cir-- cuit, however, by its energization of the sole-- noids 57 and 59, effects two results. In the first place it raises the contact bar or plate 41 which interrupts the flow of current throughthe motor, and this effects a de-A energization of solenoid 24, which perma nently opens the motor circuit until it ist again restablished by the more or less momentary closure of said motor circuit whenv contact 35 engages contact 37 andarm 29 y in the manner above described. The'energi-- Zation of solenoid 59 swings both switch arms 29 and 50 to theright and this interrupts the battery circuit, since the free extremity of armV .50 is thereby spaced from plate 35 hence sole--l noid 57 isV denergized almost immediately after the completion of the battery circuit and contact 41, again moves, by gravity, into engagement with contactsfl() and 4t2. Short as is this interruption of the motor circuit, however, it is suiiicient to effect a permanent interruption thereof in manner aforesaid. Thus when the pressure in the reservoir is lowered to. a determined amount by the with-y drawal therefrom of air for successive transmission of carriers, the motor will be auto-- matically started and said motor will con tinue in operation until the blower driven thereby has elevated the'pressure in the reservoir to the pre-determined upper limit, whereupon, the motor will be automatically stopped.

The solenoid 59 is merely an added assur-- ance-that the battery circuit will be opened to save battery current after the solenoid. 57 has been even momentarily energized, since ifthe quadrant be properly disposed and be provided with properly spaced indentations, the mere outward advance of v4through valve 63.

contact 35 may be made to first rotate the quadrant counter-clockwise until the detent rests upon lthe arcuate surface between the quadrant indentations, when, just as plate 35 engages contact52, the spring pressed detent starts to slidev down into the right hand indentation, thereby swinging arms 29 and 50't0 thev positions indicatedin dotted lines and, of course, interrupting vthe battery circuit which has already performed its function. The omission of solenoid 59 how ever necessitates a closer setting or adjustment of contact 52 than is the case when solenoid 59 is provided.

I prefer tor start the motor gradually; successively-cutting resistance out of the motor circuit whenever said motor is started. To this end the solenoid 25 is caused to actuate the rheostat arm 60 and the lower extremity .of the core of saidsolenoid 25 is connected to la piston 6l which is adapted 62. The respective upper and lower extremities of said cylinder 62 are connected withcheck valves 63-63 which open outwardly so that Awhen the piston 6l is ascending the airV in advance thereof mayl freely be expelled through the upper check valve 63 and correspondingly when piston' 61 Vis descending the air therebelow emerges Timingvalves (S4-64C are also provided; by means of which the speed of ascent and'also that of descent of said `piston 61 maybe regulated to a nicety.

As a result of these provisions when'the motor is started the resistance 26 maybe cut out at anyv Ydesiredrate and conversely when the motor is stopped, if it be desired,

Ysuch-,resistance may be cut in comparatively ssl'owly.v This resultsin a saving of wearY :and tear upon the motor and air displacing means; and since -I prefer to so automati- Ically start the motor eac-h time only after a .determined `number of carriers have been transmitted, a material Saving in power is Y effected, since power is more 0r less unnecessarily consumed, every time that the motor is started, in overcoming the inertia ofthe moving parts, etc. y

Referring nowto` the combined valve and' time elementzmechanism 1.0, it will be noted 'that the construction of this apparatus is lexceedingly simple.y It comprises a casing,

" said head is in its lowermost position. The

space below the head 67 may be placed directly in connection with the reservoir 8 through the instrumentality of a pipe 71. ln this pipe is a valve 72 which is normally held closed by means of a weight 73, or the like, but which may be opened upon the energization of a solenoid 74. This latter is in circuit with a battery 75, or Yother suitable source of electric current; being directly connected thereto, on one side, by a wire 7 (3 and the other side of said solenoid being connected to a contact 77 by means of a wire 7S. Adjacent contact 77 is a second contact 79 which is connected by a wire 80 and wire 81 to the other pole of the battery. The completion of this battery circuit is effected through the intermediacy of a switch arm 82 which preferably is mounted upon the outer extremity of a spindle 83 which carries the valve 84 disposed at the carrier admitting opening of the terminal 3. As the terminals 3 and 5 are substantially identical in construction, switch arm 82 has been indicated only upon said terminal 5 since it is upon the outer' side of thev terminal casing. lt is evident therefore that when lthe valve 84 is pressed inwardly asA upon the insertion of the carrier into the receiving terminal, circuit across contacts 77 and 79 will be completed and solenoid 74 will be energized. This results in opening valve 72 and the pressure fluid passes from the reservoir 8 through pipe 7l into the space below the piston or head G7, promptly elevating the latter and thereby opening communication between passages 9 and ll. As long as solenoid 74k continues to be energized the double headed plunger will be held in its uppermost position but immediately the said solenoid is denergized weight 73 closes valve 72 and the plunger commences to descend. The air trapped below plunger head G7, however, can only escape slowly through the air timing means, namely the restricted conduit 85; a needle valve 86 permitting of the regulation of this escape of air so that the speed of descent of the plunger valve 68 may be determined with considerable precision. l particularly desire to call attention, however, to the fact thatthe time or period during which this plunger valve is so descending is not a predetermined or Afixed one but rather that it is dependent upon the pressure of the air issuing from the reservoir, because, when increased, the pressure upon the upper surface of the plunger' head G7 will cause an accelerated descent of the plunger; while correspondingly as this pressure decreases, the speed of descent will be less. Further- I more it will be observed that the passage 87, which admits air under pressure from the reservoir 8 to and through the chamber 69, is angularly disposedwvith respect. to the axis ofthe plunger, so that as the jet of vsimplied to the transmission line, be

air emerges from said passage 87 it impinges upon the upper surface of the head 67 and it is obvious that if said air be deliver-ed from the reservcirto the transmission tube under la-relatively hiOh speed the force or downward pressure exerted by the issuing jet of air upon said upper surface of theI head G7 will begreater than when the speed of the air so delivered from the reservoiry to the transmission tube is not so great. Thus both thepressure andthe rate of flow of air delivered to the transmission tube coact to determinethe speed of descent of the timing plunger. immediately said plunger passes the port in the cylinder or casing 6G opening into pipe 1l, of course, this flow of air from the reservo-ir will cease.

ln a. system, such Vas is shownby way of cxemplification herein, the air for conveying carriers in one direction, e. g. from station B to station A, is lirst forced to travel through a tube l, which is not directly used for the conveyance of out-going carriers from the station B and there is, of necessity, and especially where the transmission tubes are of considerable length, a material ditcrence in the time during which air must be supplied from the reservoir or other source of pressure-fluid, between the time of transmitting a carrier between the stations A and B and between B and A; since in order to propel the carrier inserted at B to A the air must iiow up around through pipe l, terminal el, loop 7 and only thereafter through terminal 5, transmission tube 2 and terminal. G. 0n the other hand, when a carrier is being sent from station A to station l the air enters immediately into the carrier conveying tube. ln other words to transmit a carrier from B to A necessitates a compression of air in tube l to a pressure practically equal to that of the air delivered from the reservoir, before the carrier can be started upon its -iourney from station B to station A. l/Vhereas when'transmitting in a reverse direction there is no such necessity for compressing what may be a very ei;- tended column, so to speak, of air before theY starting of the carrier on its journey can be effected.

lf a. predetermined yand set interval time during which pressure tluid will of be irovided, regardless of the direction of transmission of carriers, there will, self evidently, be a waste of power when transmitting from, for example, station to station ,ll because this period of time will have to be sufficient to insure the transmission of carriers from B to l have accordingly provided means for insuring the delivery of pressureiiuid for one variable period of time (variable within substantially determined limits) when transmitting from station A to station B and have provided for thisV second solenoid 90, but further of the' valve operating solenoid 74 in the manner hereinafter described.

Depending from the core of the solenoid 90 is a stem 92 which carries a piston 93 and L. at, its lower extremity a bridge 94 adapted to'com'pletecircuit between a pair of contacts 95-96. The piston 93 is adapted to reciprocate in a cylinder 97; the lower 'extremity of said cylinder being connected to a check valvev98 the flap of which is pivotally mounted.l so that it may swinginwardly and freely admit air below vpiston 98 when the latter is ascending but which `will check y the flow of air from below ysaidpiston when the latter is descei'iding.V A set'screw 99 mounted in the casing of the valve-98 pro# vides means for cracking this valve, or in' other words, very slightly raisingit from its seat so that the air trapped below piston may be allowed to seep around valve 98 at any desired rate whereby to time, subject to the provisions hereinafter referred to,

the descent of said piston. rilhe'upper end of cylinder 97 is connected by means .of a

small pipe 100 with the timingconduit85- ofthe mechanism 10, above referred to; and in this pipe 100 is disposed a valve casing 101; the valve 102 of which is pressed against its seat by a spring 103,- or by gravity, if desired. TWhile this -valve has, hence,

a bias for its closed position, an arm thereof,

which vprojects upon the opposite side of the piro-bal axis 104 of said valve, is adaptedfor engagement with the core of the solenoid 90 when said core is in its lowermost position,

so 'that the weight of said core normallyv holds valve 102 open. As a result, the air escaping through conduit S passes through v pipe 100 and escapes, normally, past valve 102. The moment, however, that solenoid 90 becomes energized, in the manner above described, valve 102 closes and thel air passing `through pipe 100, insteadof escaping immediately to the atmospherev passes lon through casingv 101 and enters cylinder 97 above piston 93;l Asthis airaccumulates in Y this space, it presses said piston down with more orless forcel according to thespeed of descentof the; piston head 67 in the timing InGChaIllSll v Therefore this secondptimsV slowly7 descending.

ing instrumentality is governed or controlled by the first. Now, the upward move-' ment of stem 92, by the energization ofsolenoid 90, due to the closure of circuit at 77 7 9 in the manner vabove described, brings the bridge 94 into engagement with contacts 95 and 96 and completes a circuit through wires 105, 106, 78-and 76, which energizes solenoid 74. The continued up'- ward movement of the bridge 94 may thereafter either withdraw said bridge out ofA engagement withcontacts 95 'and 96, or-may not, as desired. It is preferable however to draw the bridge 94 out of engagement with 1 contacts 95 and 96 in order tosave battery current, especially after the insertion of the carrierpast valve 84. If bridgej'94 be above contacts'95-96, the` battery circuit willbe completely opened and solenoidv 74 will be denergized which permits weight 7 3 `to` close valve 72 and the timing mechanism 10 starts to time. closed and piston' 98 will be' more or less air from below the head 67 will pass into cylinder 97 and more or less accelerate the speed of descent of piston 93; this variation in speed of said piston depending upon the pressure of air in reservoir 8 and the rate-of iiow of said air thro-ugh passage 87.

'As bridge 94 continues to descend it will again close the battery circuit l'across contacts 95-96 and this will momentarily re-V energize solenoid 74 and re-time mechanism.Y

10. 'Immediately afterv this, valve 102 will be opened, while bridge 94 will be moved out yo f engagement with contacts 95 and 96;

again interrupting v.the batteryv circuit.` Thereafter: the timing mechanismlO willV operate exactly as if it has 'been actuated from station A. It will hence be observed" that by thus inserting a carrier in terminal 5, at station. B, theftiming mechanism 10 isl started, lpermitting the pressure-fluid toy be freely delivered tothe transmission line; but" that after the` lapse of a period. determined by the rate of descent of piston 93 andfbeforer'the flow of .air from reservoir 8 vis in@ During this interval,`

Valve102 will however Vbe terrupted by valve or piston head 68, said v timing mechanism 10 will'be automatically retimed and thereafter allowed to automatically cut off communication with thesource of fluid pressure 'substantially exactly as in the case where a'carrier is being sent from station4 A'y to stationB. It will further be observed that I am thus enabled to add to v"the length-'of timel required to sendvfa car-` rier fromstation A to station B, a sufficient additional periodvof timevto allow forthe transmission 'ofv air through tube 1 before starting the carrier atB toward A; and that Y both lof these periods of time are' subject to' variations inpressu're inthe reservoir or"` 'source-of ypressure-fluid and alsoy to the rate at vwhich l the pressureefluid is'delivered to iiov the transmission line. Practically the utmost economy is'therefore effected by the present system; substantially every factor that would result in a loss of efficiency being considered.

Considering the operation of the system as a whole, in brief therefore, the motor which operates the blower which stores the pressure-fluid in the reservoir is rendered operative but once for substantially a given number of carrier transmissions; and when it is so operated itis started and stopped most eiliciently. lhen the pressure in the reservoir attains a pre-determined amount this motor-is automatically stopped and when the. lower' pressure limit allowed for the ,operation of the` system is reached, said motor is automatically again started.

rJ'Chetl w ofipressure fluid from the reservoir is economically and efliciently governed through the instrumentality of the mechanism l0. rll`he auxiliary7 time element mechanism .comprising piston, operates, in the manner aforesaid, to automatically add the time needed for transmission in one direction over that required for carrier transmission in an `opposite direction; andeven Vthis additional time is subject to variations in the pressr-.re and rate of flow of the pressure fluid into and through the transmission tubes.

wWhile l have shown electrically operated devices, namelyl solenoids, in the several places where such .devices have beenA indicated, itis of coursecbvious that other instrumentalities may be employed. l further desire to direct attention to the fact that while prefer tov combine the valve or corresponding device whichzcontrols the flow of pressure fluid into the transmission tubes, so that it is directly and integrally attached to a part of the time element mechanism, it is by no means essential that such construction be employed, since anyone skilled in the art should be able to substitute combinations of other elements adapted to perform the functions which mechanism l0 is intended to accomplish. l'n like manner various other changes and modifications may be made throughout the system without, as above stated, departing from thel spiritof my invention. Further, while the various herein described apparatus vand combinations 0f elements are'particularly adapted to a pressure system Yand the invention has been disclosed in connection with such .a system, l do not desire to be limited in anyway, other than where in certain of the appended claims, such a pressure system is unequivocally indicated. 1

The savingv of power effected by the present invention'renders it of particular value in connection with despatch tube systems having transmissions tubesy of large diameter. llh'e fact, too that while the mechanism 10 is'dependent upon both the flow and pressure of air delivered through the transmission tube, it is nevertheless adapted to be re-timed for successive carrier insertions Without rendering operative the air impeding means or valve 68 to stop said flow of air, is of very considerable importance. The length of the additional time provided by the secondary timing means will also, obviously, be influenced by the extent and disposition kof the contacts 951-96.

rlhe provision yof time element means for establishing a more protracted carrier propellingeffort for the transmission of carriers from one station to another than for the transmission of carriers from said other to said one, is believed to be broadly new, and except where the claims drawn to combinationsincluding such means are specilically limited to pneumatic despatch apparatus, they are not to be regarded as limited in any way to the apparatus particularly described. Even in pneumatic despatch systems, in general, the ail received from gravity or other source of power may advantageously be taken account of by means of Adifferential timing mechanism such, for example, as that herein given by way of exemplication.

Similar remarks apply to the slowing down or retarding ofthe primary timing mechanism l0 by the closure of valve 102 when the supplemented or secondary timing device is actuated; and, correspondingly, the acceleration of the s'econdarytiming dcvice by the pressure exerted upon the piston thereof through the intermediacy of said.

primary timing device. Further, to the best of my knowledge it is broadly new in despatchsystems to provide means-for automatically re-timing a ktiming device which controls the duration of the carrier propelling effort. Y

l am awarethat in the system described in the aforesaid patent to Skirrow, the introduction` of a secondr carrier following a rst, re-time'sthe timing mechanism, but such system obviously does not provide automatic means such as have just been referred to, the second carrier being inserted through the intermediacy of an operator who thereby immediately retimes the mechanism. This automatic re-timing ortime-extension feature should prove of especial value where,

for example, the distance between stations Having thus described my invention What I claim is:

l. In a pneumatic despatch system, the combination of a receptacle adapted .to contain air at a pressure different from that of the surrounding atmosphere, means for creating 'this diiference in pressure, mea-ns forV controlling the last mentioned means Whereby to insure said di''erence in pressure beingmantained adequate for carrier transmission purposes, a tube for transmitting carriers, and means, co-acting With said tube for rendering said difference in pressure eective for carrier transmission purposes, for a normally limited interval of time, said last mentioned means including a time element mechanism for automatically limiting the carrier transmitting flow of air after the lapse of a variable period of time sufficient to transmit a carrier effectively through said tube under the pressure conditions present at such time in the system, said time element mechanism provided ivithmeans for var ing, said time period substantially in accordance with the operating pressure in said system.

2. ln a pneumatic despatch system, the combination of a receptacle adapted to contain airv at a pressure diilerent from that of the surrounding atmosphere, means for creating this difference in pressure, means for controlling the last mentioned means Whereby to insure said difference. in pressure being maintained adequate for carrier transmission purposes, a tube for transmitting carriers, and means, co-acting with said tube for rendering said difference in pressure ellective lor carrier transmission purposes, for a normally limited interval of time, said last mentioned means including a time element mechanism for automatically limiting the cari-ier transmitting iioiv 'of air after the lapse of a variable period or" time sulficient to transmit a carrier `effectively through said tube under the pressure'conditions present at such time in the system, said time element mechanism provided with means for varying said time period substantially in accordance withv the speed of floiv of air through said tube.

3. ln pneumatic despatch system, the combination of a receptacle adapted to contain air at a pressure dierent from that of the surrounding atmosphere, means for creating this difference in pressure, means ior controlling the last mentioned meansl i for a normally limited interval of time, said last mentioned means including a mechanism for automatically limiting the carrier pressed air supply, a valve for controlling the iloiv of air from said supply through said tube, means for opening and for controlling the subsequent closure or said valve, said last mentioned-means including a tim- Ving means controlling said valve closure and operating dependently of the rate of movement of theV air moving through said tube, and means, operable from said station, for rendering operative the valve opening and timing means. i

5.111 a pneumatic despatchsystem, the combination of a transmission tube, a station having means `for permitting'the introduction oit' carriers into saicL tube, an air simply, comprisinga reservoir and means `tor automatically charging said reservoir with compressed'air from time to time in accordance ivith the vdemands o said system, and means for conserving air from said supply comprising a valve for controlling the loiv of said'air through said tube, means for opening ,and for controlling the subseqiient'closure of said valve, said last mentioned means including variably acting timing means controlling said valve closure and having provisions to cause said timing means tc operate dependently of the pressure of the air moving through said tube, and means, operable from'said station, for rendering operative said valve opening and timp ing means.

6.5 ln a pneumatic despatch system, the combination of a transmission `tubea plurality of stationsfeach having means for permitting the introduction of carriers into said tube, a compressed air supply, a valve for controlling the flow of air from said supply, through said tube, means for ogening and `for controlling the subsequent closure ofy said valve, said-meaiis including yvariably acting pressure lcont-rolled timing means controlling said valve closure and operating dependently of the pressure 4of thel air moving through said tube, and means,

operable from any one ol said stations, forV rendering operative said valve opening and timing means, at least one of said stations ybeing relatively remote from said valve.

7. ln a pneumatic despatch system, the

combination of a transmission tube, a station having means for permitting the introduction oi.' carriers into said tube and means for establishing for a normally limited period of time, a carrier transmitting flow ot air through said tube, said means including a part adapted to normali" impede said lioW, means for rendering said air impeding part substantially inoperative, timing means controlling trie return ot said part to its normal position and operating dependently of the pressure of said air, and means, operable from said station, for rendering operative said tivo last mentioned means, said timing means adapted to be re-timed for the transmission of successive carriers introduced into said system during trie time that said timing means is operative, and said air impeding part being adapted to remain substantially 'Wholly inoperative When said timing means is so re-timed and being out ot the path of travel ot said air at such times.

8. ln a pneumatic despatch system, the combination of a transmission tube, a plurality ot stations having means for permitting the introduction of carriers into said tube, and means tor establishing, for a normally limited period of time, a carrier transmitting ilow of air through said tube, said means including a part adapted to normally impede said flow., means for rendering said part substantially inoperative, variably acting timing means controlling the return of said part to its normal position and operating dependently ot the pressure of said air,

said timing means having a movable controlling element thereof disposed for contact with the air current and variably movable in accordance with the variations in pressure ot said air, and means, operable from any one oi said stations, tor rendering operative said tivo last mentioned means, said timing means adapted to be re-timed for the transmission of successive carriers introduced into said system during the time that said timing means is operative, said air impeding part remaining substantially wholly inoperative When said timing` means is so re-timed.

9. n a pneumatic despatch system, the combination ot a carrier, with a looped transmission tube connecting a plurality of stations and means for establishing for a normally limited period, a carrier propelling current of air in said tube, said means including timing means for controlling the duration ci said current, said mechanism having provisions, substantially independent of the travel of carriers, for insuring a longer loiv of air tor transmitting carriers from one ot said stations to another station than for transmitting carriers 'from said other to said one.

10. ln a pneumatic despatch system, the combination of a carrier, With a transmisemesse timing mechanism for controlling said last f mentioned means, said mechanism having provisions, substantially independent of the travel ot carriers, for insuring a longer flow ol air for transmitting carriers from one of said stations to another station than for f transmitting carriers from said other to said one. v

1l. In a pneumatic despatch system, the combination of a carrier, with pneumatic transmission means connecting a plurality of stations andl means for establishing, tor a normally limited period, a carrier propelling current of air in said transmission means, said means including a timing mechanism for controlling said current of air, said mechanism having provisions for insuring a longer flow of air for transmitting carriers from one of said stations to another than for transmitting carriers from said other to said one. v

12. In a despatch system, the combination of a carrier, with carrier guiding means connecti ng a plurality of stations and means for establishing, vfor a normally limited period,

a carrier propelling eli'ort for transmitting carriers from one ot said stations to another, said means including a timing mechanism for controlling said effort, said mechanism havin?` provisions for insuring a more protracted eiort for transmitting carriers from one station to another than for transmitting carriers from said other to said one.

13. In a despatch system, the combination of a carrier, with carrier guiding means connecting a plurality of stations and means for establishing, for a normally limited period, a carrier propelling effort for transmitting carriers from one of said stations to another, said means including timing mechanism, Voperable mechanically, at least in part, .tor controlling said effort establishing means, said mechanism having provisions tor insuring a more protracted effort for 'ransmitting carriers from one station to anothery than for transmitting carriers from said other to said one.

14. ln a despatch system, the combination ot a carrier, With carrier guiding means connecting a plurality of stations, and means for establishing, for a normally limited period, a carrier propelling effort for transmitting carriers fromA one ot said stations to another, said means including timing mechanism, operable electrically, at least in part, tor controlling said effort, said mechanism having provisions for insuring a more protracted eiiort for transmitting carriers from one station to another than for transmitting carriers from said other to said one.

15. ln a despatch system, the combination pui vnecting a plurality of stations and means forY of a carrier, with carrier guiding means conestablishing, for a normally limited period, a carrier propelling effort for transmitting carriers from one of said stations to another, said means including diierential timing mechanism for automatically permittingthe expenditure of more power for carrier transmission purposes for Vcarriers traveling in one direction than for carriers traveling in another direction.

16. In a' despatch system, the combination of a carrier, with carrier guiding means connecting a plurality ofstations and means for establishing, for a normally limited period, a carrier propelling effortfor transmitting carriers from one of said stations to another, said means including differential timing mechanism for permitting the eX- v penditure of more power for carrier transmission purposes or carriers traveling-in one `direction than for carriers traveling in another direction, said mechanism having provisions for varying the time determined thereby substantially according to the amount of power available to Vbe so eX- pended.

17. In a despatch system, the combination of a carrier, with carrier guiding means connecting a plurality of stations and means for establishing, for a normally limited period, a carrier propelling effort for transmitting carriers from one of said stations to another, said means including differential timing mechanism for permitting Vthe eX-,. penditure of more power for carrier transmission purposes for carriers traveling in one'direction than for carriers traveling in another direction, said mechanism havingv provisions for varyingthe time determined` therebyv substantially according to the carrier propelling effort possible to be estab lished at such time. y

. 18. In a despatch system, the combination of a carrier, with carrier guiding means con- Y necting a plurality of stations and means for establishing, for a normally limited pe for transmitting carriers from one of said,

stations to another, said means including a plurality of interconnected timing devices adapted to co-act to variably' control the enpenditure of power for Vcarrier transmission' purposes in accordance with the service requirements of saidsystem, said devices pro# vided witlrmeansfor effecting a successive actuation thereoil".v A v y20. In a' despatch system, the combina-- tion of a carrier, with carrier guiding means connecting a plurality of stations andmeans for establishing, for anormally limited period, a carrier propelling e'ort for transmitting carriers from one of said stations to another', said means includinga plurality of timing devices for controlling the expenditure of power for carrier transmissionpurposes' in accordance with ,the service requirements of said system, and connections betweenl said `timing, devices for determining the rate of actuation of one of other. l Y

21.1 In a despatch system, the combination of a carrier, vwith carrier guiding means connecting a plurality of stations andV means for establishing, for a normally limited period, ,al carrier propelling effort for transmitting carriers from one of ,said stations'to another, said means including a f plurality of timing devices forcontrolling the expenditure of power for carrier trans-v mission purposes in accordance with the service requirements of said system, and

connections between said timing devices for controllingfthe rate of actuationof one .of said devices said devices.

22. In a despatch system, the combination of a carrier, with carrier guiding means connecting. a plurality of stations and means'forestablishing, for a normally limited period, a carrier propelling etlort for transmitting carriers from one of said stations to another, vsaidmeains including a plurality of timing Vdevicesfor vcontrolling the expenditure of power for carrier transv-` mission purposes, and connections lbetweenv` said timing devices for retarding the actuation of one of said devices substantially lin accordancewith therequirements of service conditions in said system. 23. In a despatch system,the combinatio of a carrier,` Vwith carrier guidingv means connecting a plurality of stations and means for establishing for a normally limited i period, a carrier propelling effort for. transmitting carriers from one of said stations to A another, said means including atiniing 'device provided with means for slowing down the normal actuation thereoi:l for a period of limited duration in accordance withV the requirements of service conditions in said system. v I

24. In a despatch-system,the combination of a carrier, with` carrier guiding meansy connecting a plurality of stations and f means for establishing, for a normallylim ited period, k'a carrier propelling etort for by the actuation of another of said devices by the rate of actuation of an- Y transmitting carriers from one of said stations to another, said means including a timing device provided with mechanism for temporarily slowing down the normal actuation thereof in accordance with the requirements of service conditions in said system.

25. ln'a despatch system, the combination of a carrier, with carrier guiding means, a

source of power for transmitting carriers in the direction of the length of said guiding means, means, including a timing mechanism for controlling thev delivery of said power trom said source, and means, governed by the rate at which power is delivered from said source oi power, for automatically accelerating the action of said timing mechanism.y

26. In a despatch system, the combination of a carrier, with carrier guiding means, means for establishing a carrier propelling effort for transmitting carriers in the direction of the length ot' said guiding means, means for limiting the duration of said effort, including a primary and a secondary timing means and connections between said means for re-timing said primary means through the intermediacy of said secondary means.

27. ln a despatch system, the combination oit' a carrier, with carrier guiding means eX- tending between two stations, means for establishing a carrier propelling ettort for transmitting carriers in the direction of the length of said guiding means, means, in-

cluding two timing mechanisms, for limiting the duration of said effort, means at one oi said stations for rendering both of said mechanisms operative and means atV the other of said stations for rendering one of said mechanisms operative.

28. ln a despatch system, the combination of a carrier, with carrier guiding means eX- tending between two stations, means for establishing a carrier propelling effort for transmitting carriers between said stations, means, including a timing mechanism, for limiting the duration of said ell'ort, and means, operable from one of said stations, for extending the time during which said effort is exerted.

29. ln a despatch system, the combination of a carrier, with carrier guiding means eirtendingbetween two stations, means for establishing a carrier propelling effort for transmitting carriers'between said stations, means, including a timing mechanism, for limiting the duration of said effort and automatic means, initially operable from one of said stations, for extending the time during which said eiiort is exerted.

30. ln a despatch system, the combination of a carrier, with carrier guiding means eX- .tending between two stations, means for establishing a carrier propelling eort for of said stations, for varying the time durl ing which saideort is exerted.

3l. In a despatch system, the combination of a carrier, with carrier guiding means eX- tending between two stations, means for establishing a carrier propelling eort for transmitting carriers between said stations, means, including a timing mechanism, for limiting the Vduration of said effort, and means, dependent upon the efhciency of said effort and independent of said carrier for automatically extending the time during which said eiort is exerted.

32. ln a despatch system, the combination of a carrier, with carrier guiding means eX- tending between two stations, means for establishing a carrier propelling ettort for transmitting carriers between said stations, means, including a timing mechanism, for limiting the duration of said eort, and means for automatically re-timing said timing means after the lapse of a material interval of time subsequent to the initial subjection of said carrier to said effort, said automatic means adapted to operate independentlyof the travel of said carrier.

33. ln a despatch system, the combination or a carrier, with carrier guiding means eX- tending vbetween two stations, means for establishing a carrier propelling eort for transmitting carriers between said stations, means, including a timing mechanism, for limiting the duration of said effort, and auX- iliary means for re-timing said timing means after the lapse of an Vinterval ci time, dependent upon operating conditions in said system, subsequent to the initial subjection of said carrierto said effort.

34. ln a despatch system, the combination of a carrier, with carrier guiding means, means for establishing a carrier propelling effort for transmitting carriers in the direction of the length of said guiding means, means, including a timing mechanism, for limiting the duration of saidv effort, and means for automatically :re-timing said timing means after the lapse of a material interval of time subsequent to the initial subjectionof said carrier to said etfort.

35. In a despatch system, the combination of a carrier, with carrier guiding means connecting a plurality of stations, means for establishing a carrier propelling elort for transmitting carriers from one of said stations to another, twol interconnected timing devices for controlling the expenditure of power for carrier propelling purposes in accordance with the service requirements oli' said system, said system having provisions for varying the rates of actuation of both of said timing devices.

36. In a pneumatic despatch system, the 'combination of a transmission tube, a station having means for permitting the introduction of carriers into said tube, an air supply, a valve for controlling the flow of air4 from said supply through said tube, means for opening and for controlling the lsubsequent closure of said valve, said last mentioned means including a timing means controlling said valve closure and operating dependently of the rate of movement of the air moving through said tube, a movably mounted part of said valve opening and controlling means bein'g directly in the path of the current of said air and subject to the 15 pressure of said air exerted upon said part, a

CHARLES P. HIDDEN.

Witnesses:

ISAAC KRAFSUR, ETHEL M. JORDAN Copies of this patent may be obtained for iive cents each, by addressing the "Commissioner of Patel-ith.

Wlshington, D. G." 

